Harry Potter and the Mystery of the Box
by herecomesthesun93
Summary: The Doctor and Donna find themselves in a popular book! But how did they get there? Who can help them figure out how to get them home? D/C: JK Rowling owns Harry Potter. BBC owns Doctor Who
1. Prologue

Prologue

Harry was having a hard time believing this was real. A part of him still expected that this was just a vivid dream, that he would wake up at any moment still under the stairs. He walked along with his very first friend, coins jangling in his pocket, a smile stretched across his face.

"Might as well get yer uniform," Hagrid commented with a gesture toward Madam Malkin's. "Listen, Harry, would yeh mind if I slipped off fer a pick me up in the Leaky Cauldron? I hate them Gringotts carts."

Harry nodded his approval, and watched for a moment as Hagrid shuffled off down the alley. Heart pounding, Harry slipped into the shop. Nervousness welled up inside him.

"Hogwarts, dear?" The cheerful witch toddled up to him. She was short and had a round build. "Got the lot here - a young man and woman getting fitted up just now, in fact."

She led him to the back of the shop which had a long, rectangular shape. Along one wall had mirrors across the whole thing. Pedestals stood at intervals near the center of the room. A line of chairs faced the other wall.

A boy with a pale, pointing face was standing on a pedestal as another woman pinned up his school robes. A girl with long, dark hair and light skin sat on one of the chairs, reading a magazine titled, "important wizarding bands in the modern age." A wrapped parcel sat beside her, asserting that she had already been fitted.

"Hello," the boy commented. "Hogwarts too?"

"Yes." Harry replied.

The girl looked up from the magazine at Harry's response.

"My father's next door looking at books and mother's up the street looking at wands." The pale boy responded. "Then I'm going to drag them off to look at racing brooms. I don't see why first years can't have their own. I think I'll bully father into getting me one and I'll smuggle it in somehow."

At this the girl let out a slight snort of laughter. The boy turned around and glared hat her darkly. He turned around and continued talking.

"Have you got your own broom?"

"No." Harry responded.

"Play Quiddich at all?"

"No."

It didn't pass the girls notice that Harry was getting more and more nervous by the second.

"I do - Father says it's a crime if I'm not picked to play for my house, and I must say, I agree. Know what house you'll be in yet?"

"No." Harry stated.

The girl opened her mouth to cut in, but was interrupted by the pale boy.

"Well, no one really knows until they get there, do they, but I know I'll be in Slytherin, all our family have been - imagine being in Hufflepuff, I think I'd leave, wouldn't you?"

The girl's head dropped as her magazine fell to the floor.

"Mmm." Harry muttered out of a lack to say. He hoped he'd have something to add to the conversation.

"I say, look at that man!" the boy called out suddenly, gesturing to the shop window. The girl whipped around in her chair to see a massive man clutching two ice creams.

"That's Hagrid." The girl grinned slightly at Harry's newfound pleasure. "He works at Hogwarts."

"Oh," the boy responded. "I've heard of him. He's a sort of servant, isn't he?"

"He's the gamekeeper."

"Yes, exactly. I heard he's a sort of savage - lives in a hut on the school grounds and every now and then he gets drunk, tries to do magic, and ends up setting fire to his bed."

"I think he's brilliant." Harry snapped coldly.

"Do you?" sneered the boy. "Why is he with you? Where are your parents?"

The girl's head snapped up, ready with a question, but was cut off as Harry responded shortly.

"They're dead."

"Oh, sorry." He continued, not noticing the girl's gasp of recognition. Her hands balled into fists, not noticing her magazine was still on the floor.

"Stop talking." She commanded.

"No one asked you." The boy sneered at her."But they were our kind, weren't they?" He continued to Harry.

"They were a witch and a wizard, if that's what you mean."

"I really don't think they should let the other sort in, do you? They're just not the same, they've never been brought up to know our ways. Some of them have never even heard of Hogwarts until they get the letter, imagine. I think they should keep it in the old wizarding families. What's your surname, anyway?"

"That's you done, my dear." Madam Malkin stated before Harry could reply.

Relieved for an excuse to go, he hopped off the footstool, and as the witch wrapped up his robes, he stepped toward the girl, picked up her magazine, and handed it to her.

"Thanks." She muttered under her breath with a smile. "Sorry about him, by the way."

"Well, I'll see you at Hogwarts, I suppose," the boy said at his back as he left.

A/N: This is my first fanfic so please review! I think I need some constructive criticism. I promise I have a very good reason for my OC! If you are anything like me, I don't really care for OC's because I feel like they're always too Mary Sue-like. I posted the first chapter at the same time, so give it a read and let me know what you want to see in later chapters.


	2. Chapter 1

Chapter 1

Disclaimer: Harry Potter belongs to JK Rowling. Doctor Who belongs to BBC.

 _"It's no good sitting there dreaming. No one's gonna come along with a magic wand and make your life all better." - Sylvia Noble (Partners in Crime)_

It was a nice, quiet night in the TARDIS. It was one of those rare times when it was actually peaceful. There was nowhere to go. Everyone was safe. The Doctor savored his moment of relaxation, reading luxuriously in the control room.

The funny things about quiet moments in the TARDIS, however, was almost every time, they ended abruptly. A sudden jolt shook the entire police box to such a degree that the Doctor's book fell from his hands as he quickly found something - anything - to grab on to. He regained his balance by reaching out to one of the many cords that hung from the ceiling.

"Oi! Spaceman!" Donna yelled out into the control room, tugging on her bathrobe over her nightgown. "What would that be, then? Trying to rile me up when I'm trying to sleep?" she demanded.

"Wasn't me!" he insisted, bounding toward the center control. "It doesn't make much sense, what just happened. The Rexel system is practically empty! The planets here uninhabitable!"

"That's what you said about Midnight, innit?"

"That was different! The acidity in the air here would cut through steel. Not even the Daleks could sustain life in this galaxy." He explained, concentrating on the screen that sat in front of him. He tried a few things for a straight answer, even resorting to his sonic screwdriver, but to his disappointment, brought up nothing.

"I don't understand!" The doctor ran his hand through his bed hair. "How is this-"

Another great jolt shook through the TARDIS once again, throwing the doctor into Donna, pushing her to the ground.

"Get off me!" She demanded, pushing him with great force for a woman of her size. He immediately complied, sliding off her with impressive speed.

The doctor sprang to his feet as the time machine took off with its trademark whooshing sound.

"We're taking off!" The Doctor exclaimed with a tinge of confusion in his voice. "Where are we going?"

"Well, how am I supposed to know? You're the alien, not me!" Donna replied, her voice laced with sarcasm.

"I wasn't asking you." He responded.

"What? Am I supposed to believe that you actually talk to a machine?"

"The TARDIS is alive."

"What? Really?" She looked around the large room.

"Where are we?" The doctor muttered. He inched his way toward the door, and with Donna behind him, slowly and carefully eased the door open.

"What?" He cried. "Wha... What?"

Donna followed him out of the police box, completely shocked.

"Are we-" she trailed off.

"I think so." The doctor replied. He looked around, soaking up the sights that rushed over him. To his right stood a great castle at the base of a vast lake. It was evening, and the lights from the windows twinkled down over the grounds. To his left stood a fenced oval field with three hoops on each end that reached high into the sky. The TARDIS was shielded at the edge of the incredibly dense forest.

"Hogwarts castle." He stated with a tinge of glee.

"How in the bloody hell is this possible?" Is this really happening?" Donna laughed. "You never told me there really are wizards in England!"

"There aren't." He explained. "I think we're in the book. Look, try to focus on anything farther than 20 meters from you."

Donna squinted. Though everything close to her was clear as day, she couldn't focus on anything in the distance. It was almost as if she suddenly needed a prescription for nearsightedness.

"Well, that's annoying." She exclaimed. "What's causing that, then?"

"We're in the story. I expect the closer we get to the location of the plot, the clearer things will become. Like a bubble. The story is in the bubble, and if we stay inside, things are clear, but if we step outside, it'll get hazy."

"Oh, that clears things up then, doesn't it?" Donna stated, pointing to the horseless carriages that declared they were at the beginning of a year.

"Shall we go in?" The doctor asked, gesturing to the castle.

"Not dressed like this, I won't."

The doctor waited outside while Donna ran back into the TARDIS to get dressed. Some time later, she emerged in a simple green blouse and jeans. She'd fixed her hair in a ponytail.

"D'you think we'll be able to mess up the story?" Donna asked. "If we're in the book?"

"I don't think so, no. The story has already been told. As long as we do our best to stay out of the main story. You've read the books, you know which characters to stay away from."

"Like them." She pointed.

There they were. It was not at all like the movie had portrayed them, and Donna didn't really know what to expect, really. Ron was startlingly tall. Hermione was vastly less pretty. Harry's hair was sticking up all over the place. There was a fourth girl with them, short, with very long, shiny dark hair. The doctor and Donna quietly observed as they trotted away from the horseless carriages to the entrance of the castle.

"You fainted, Potter? Is Longbottom telling the truth? You actually fainted?"

The two travelers watched as Draco Malfoy elbowed Hermione as he rushed up the steps to the castle. He turned to block Harry's way, glee etched across his face.

"Shove off, Malfoy," they heard Ron respond to him.

"Did you faint as well, Weasley?" Malfoy called out loudly. "Did the scary old dementor frighten you too, Weasley?"

Donna looked up at the doctor, who was staring at the confrontation the characters were having with one another.

"Book three. We're in the third book. But _why_? Why now? I can't figure it out." The Doctor muttered

"I don't understand what you mean." Donna replied. "Why now? Does it matter what book we are in?"

"Yes," he whispered in reply. "Why not the first book? Something important happened near this part. That's why we're here." He continued observing.

They watched together as Hermione poked Ron in the back to get him to rush up the steps. The four students, Harry, Ron, Hermione, and the fourth girl the Doctor didn't recognize joined the vast amount of students flooding into the castle.

"Did you notice any difference between the book and now?"

"Dunno. I've only read them through the one time."

"How many main characters are there?"

"Three. Harry, Ron, and Hermione."

"There was a fourth this time." The Doctor said thoughtfully. "I think she's the one we need to talk to. She isn't in the book. She shouldn't exist, so why is she here?"


	3. Chapter 2

Chapter 2

Disclaimer: Harry Potter belongs to Jk Rowling. Doctor Who belongs to BBC.

 _ **"**_ _It seems to me there's so much more to the world than the average eye is allowed to see. I believe, if you look hard, there are more wonders in this universe than you could ever have dreamt of." - Vincent Van Gogh (Vincent and the Doctor)_

It was a recurring theme at the end of every start of term feast that the characters were always very tired and sleepy, so the Doctor and Donna had agreed to try and talk to the strange girl the next day. So when the time came for classes, the pair jubilantly entered the castle with an undeniable taste of excitement on their lips.

"We'll need to be careful." He commented to Donna. "This is the third book. The one with Sirius Black. The teachers won't take well to unidentified strangers."

She nodded her understanding.

"Doctor, these people..." She trailed off in confusion.

"They're hazy. Filler characters. We need to get to the main characters. Everything will get steadily clearer."

"Like up there." She pointed.

The main staircase and the floors above were noticeably more defined.

"Yes, that's right." The Doctor dropped his voice down to a hush as he observed. The bubble seemed to be growing; the haze was slowly lifting. In what felt to be no time, the Doctor and Donna could see everything in perfect vision.

They watched Harry, Ron, Hermione, and the fourth girl descend the magnificent marble staircase to breakfast.

"We need to find a way to get her away from the others," the Doctor commented.

"How should we go about that?" Donna asked in reply.

In answer, the Doctor pulled out his sonic screwdriver, and pointed it at the girl's messenger bag. It split open, and books, quill and parchment tumbled out and landed at the base of the stairs.

"Blimey!" They heard her call in surprise. "I wonder how that happened."

"Do you want us to help you clear up?" Hermione called down to her as she sprinted for her books.

"No, it's ok. Save me some hotcakes, and make sure Percy doesn't drink all the coffee, will you?"

"Ok, see you in there." Harry responded as they inched around her.

The girl pulled out a white wand from her pocket and pointed it at her ripped bag.

"Reparo." She muttered. The bag seamlessly flew back together and she started piling her books back inside.

"I took that from the fourth book." The Doctor smiled. "It worked when Harry wanted to talk to Cho." Together, he and Donna made their way toward her.

"Hello," the Doctor greeted the girl. "We're here investigating the escape of Sirius Black." He flashed her the psychic paper.

"You're from the ministry?" She asked. "If you're investigating Black, what are the Dementors for?"

"Protection. Dementors are guards, not investigators." He responded.

The pair of them stood as the girl finished clearing her mess.

"We were hoping we could ask you a couple questions." The doctor continued.

"I don't know anything." She responded, a touch of insult hidden in her voice.

"I know. It's just standard procedure."

"Oh... Well, I guess so."

"Fantastic." The Doctor tucked away his psychic paper.

"What's your name?" He asked.

"What's that got to do with Sirius Black?"

"We need to document everyone that gives a statement." Donna chimed in.

"Lyra."

"Lyra?" The Doctor's eyes widened with excitement. "Like the constellation?"

"Yes. At the side of Draco, means a stringed instrument in Latin." She responded, taken aback by the Doctor's enthusiasm. "Lyra Lestrange."

"Oh, that's a brilliant name!" The Doctor exclaimed. "Oh, wait, did you say Lestrange?" He asked, his jubilance ending nearly as quickly as it came.

"Yes, but I'm surprised you didn't know that, coming from the ministry. Everyone knows my uncle Lucius. He raised me."

"Are you in Gryffindor house?"

"Yes, but what's that got do do with-" Lyra started.

"Mr Black was in Gryffindor house as well."

"Really? Are you implying that I know something? Because I don't." She responded adamantly. "I'm going to have breakfast now. Nice talking to you."

Before the Doctor could get another word in, she twirled on the balls of her feet and surged forward into the great hall.

"That went well." Donna joked.

"Yes." The Doctor replied. "It did. At least we know who she is."

"What next?"

"We go back to the grounds. I know what's relevant about this book. It's the book the Dementors show up in. I don't think it's coincidence we showed up on the same day they made an appearance."

They walked across the grounds in silence for a moment. Donna took the time to appreciate how beautiful the castle really was.

"Why did she get so defensive?" Donna finally implored, hoping to reach some understanding.

"Well, Lyra and Sirius are related. She didn't take it well when we mentioned that he was in the same house as her because she wants to be better than Black. She took the similarities in their stories as a slap in the face, like we were accusing her of aiding him. At this point in the story, they still think he was a bad guy."

"So, she's a good character, then?"

"I believe so. She's definitely a main character. She has a strong role in the story. I just can't figure out why she isn't in the book."

It really didn't take much time to reach the gates to the grounds. Donna kept blinking, adamant that she would never get used to the book haze. The farther from the castle they got, the murkier things seemed to get.

They inched closer to the gates to get a better look at the Dementor, and as they did so, a sense of hopelessness seemed to grip them both. The Doctor especially had a hard time fighting it. Terrible things began running through his head. Among others, the day he executed Gallifrey in the time war and the time he said goodbye to Rose were the moments that stood out to him the most. The pain he recalled was pressing. Both his hearts began palpitating. He had a hard time drawing breath.

Donna began backing up as the Dementor turned toward her. She couldn't see into its face, but she could still tell it was gazing into her very soul. She definitely felt it was a foreboding threat.

"Doctor!" She called out warningly. She turned toward the Doctor to see him slip to the ground, desperate for air. The Dementor began advancing, edging around the gate to get closer to them.

"Doctor!" Donna called again, panic searing through her. The Doctor pulled out his sonic screwdriver, and with immense difficulty, pointed it at the Dementor. It let out a horrible choking sound in response to the sonic blast. It grasped its throat, and with a terrifying croaklike rattle, it managed to screech out.

"You!" It called out as it pointed with its long, pale fingers. "You did this to us!"

It swooped down upon the Doctor with his right hand, and gripped Donna with the other. The Dementor's hands were getting progressively tighter. Donna cried out in pain, whilst the Doctor rummaged through his pockets for something to reverse the situation he found himself in. It would appear that he wasn't quick enough, however, as the two travelers disappeared from the Dementor's hands in a great burst of deep purple light.


End file.
